Have you noticed a plethora of puppies on your Facebook page? This is why people are posting them.

When I first noticed the pictures on my Facebook feed, I assumed that something was going on in my hometown that was prompting my old Pennsylvania friends to post pictures of their dogs on social media. But then I noticed that a triathlon friend from Maryland was posting pictures of her dog on the same site, followed by an old work buddy from California. I figured something special must be going on — and I was right. That something special is Anthony Lyons, and he is the Anthony of "Photo Doggies For Anthony."

Anthony Lyons is a 16-year-old from Arizona who was diagnosed with lymphoblastic leukemia last year. Lyons is currently undergoing inpatient chemotherapy treatments, and one thing that keeps him going is the pet therapy offered at the hospital where he is being treated. Here's an example:

Hi Anthony, this is Rocco he is a timber wolf/malamute mix he weighs in at 225 pounds from North Dakota hope you feel better soon. (Photo: Carl Olson/Facebook)

“It really helps, the pet therapy,” Anthony told Fox 10 Phoenix. “Like I can be in here having a really bad day and then one of the dogs will show up and it will be the highlight of the day.”

When Anthony's family and friends realized how important these pet therapy visits were to Anthony, and how down in the dumps he would get when the dogs weren't available to come visit, family friend Roberta Lucero-Koron set up a Facebook page titled “Photo Doggies for Anthony” to encourage Facebook users to submit pics of their dogs to cheer Anthony up.

The page read: “Hi all, my friend Kristen Lyons has her son Anthony at Phoenix Children’s hospital. Some days he gets doggy visits and some he does not. They make him smile. I thought if I create this event, you can post a picture of your dog to help make him smile. His mom shows them to him and he smiles."

Since the page was created, more than half a million people have posted pictures of dogs and cats and all kinds of critters in an effort to cheer up Anthony. “When I’m in the hospital bed all day my mom goes through all the pictures, she sees them all,” Anthony told Fox 10 Phoenix. And while he says he loves all of the pictures, he admits that the funny ones are his favorite.

Sadly, one bad poster decided to inject some negativity onto the site so the original "Photo Doggies for Anthony" page had been taken down. But Anthony has started a page with the same name and the pictures have been just kept on rolling in.